1. Field of the Invention
The present invention relates to an information processing apparatus which inputs image data, adds additional information to the input image data, and outputs that image data, a control method thereof, and a computer readable storage medium.
2. Description of the Related Art
A digital camera which acquires GPS information upon image capturing, and adds the acquired GPS information as metadata has been proposed. Using such a digital camera, the locations where images were captured can be easily confirmed later.
However, since it is easy to edit the GPS information added to the image data, if the GPS information is used for security applications that authenticate the image capturing positions of image data, its evidential capacity is poor.
In order to solve such problem, Japanese Patent Laid-Open No. 2000-215379 has proposed a technique that enhances the evidential capacity of metadata including GPS information and image data. According to Japanese Patent Laid-Open No. 2000-215379, a digital signature is generated and added to metadata including GPS information, and image data upon image capturing. If the metadata or image data has been altered after image capturing, the alteration can be detected by verifying the added digital signature.
On the other hand, GPS information is normally received as a radio wave, and is acquired based on the received radio wave. Hence, if the radio wave receiving condition is poor, since GPS information cannot be acquired, it is difficult to add GPS information to image data.
In order to solve such problem, Japanese Patent Laid-Open No. 10-56609 has proposed a technique that can add GPS information even at an image capturing position where the radio wave receiving condition is bad. According to Japanese Patent Laid-Open No. 10-56609, GPS information acquired at an image capturing position where the radio wave receiving condition is good is held in advance inside a camera. The radio wave receiving condition is checked at the time of image capturing, and when the receiving condition is bad, the GPS information held inside the camera is added in place of that upon image capturing. In this way, even when an image is to be captured at a place where the radio wave receiving condition is bad, the GPS information can be easily added to that image.
However, with the related art, when the GPS information is not added to the captured image data, the following problem occurs. That is, it is difficult to identify whether the GPS information could not be acquired due to a bad radio wave receiving condition at the time of image capturing or the user did not set the camera to add GPS information. Thus, for example, the photographer can easily set not to record an image capturing position according to his or her intention, and the related art is not suited to security applications that force to record the image capturing position and authenticate it.
When the radio wave receiving condition is not good at the time of image capturing, GPS information acquired at an image capturing position where the radio wave receiving condition is good is held in advance inside the camera, and can be added to an image as that upon image capturing. For this reason, the actual image capturing position may have a large difference from the position where the GPS information is added to an image, and the related art is not suited to security application that authenticate the image capturing position.